In New York, protesters have moved to a sidewalk near the Stock Exchange

Protesters plan for May 1 to be their first large-scale demonstration of the year

New York (CNN) -- In the spirit of spring rebirth, the Occupy movement is ramping up activities as warm weather blankets the country. But while the season is typified by a reawakening of life outdoors, demonstrators are using sleep to get their points across. They call it "sleepful protest."

The sleeping bags started appearing on the corner of Wall and Broad streets across from the New York Stock Exchange on April 9. A civil rights attorney sympathetic to the Occupy movement provided the legal justification for the move in the form of a court ruling from 2000. A federal district court judge said people can sleep on sidewalks as a form of political expression as long as they take up no more than half of the sidewalk and don't block any doors.

For the past few nights, dozens of Occupy Wall Street protesters have slept on a patch of concrete a stone's throw away from the traders and stock brokers who are the targets of their message. "The goal here is to not violate the law and not give the police a reason to move the group," said Ted Schulman, who has taken part in Occupy demonstrations for several months.

Every morning, they talk about income inequality and the role of big money in politics as commuters pass by on their way to jobs in the Financial District. Most people who work in the area seem indifferent.

So-called sleepful protests have popped up elsewhere in the country with varying degrees of success. In Washington, police have been less accommodating, while in Los Angeles, protesters have taken to sleeping outside Bank of America branches, a frequent target of the Occupy movement. Similar sidewalk sleep-ins are taking place in Boston and Atlanta.

The protesters on Wall Street don't expect their sleep-in to grow into an encampment like the one that became home to hundreds of people at nearby Zuccotti Park.

"I view this as the pre-campaign. I certainly doubt that this will still be here May 1st when the big rallies start," Schulman said. "My guess is by that point, they'll have taken control of this space again."

Occupy organizers are calling for large-scale demonstrations across the country on May 1 in conjunction with the labor movement's International Workers Day.